“Extension” - is the extension of the telephone line (PBX) or the Centrex system. It works as an association and allows calling to certain telephone sets without the necessity of dialing the telephone number, but only by dialing a short combination of digits, reaching the desired subscriber.
ShoreTel Sky is the modern phone system for today’s agile, mobile and always-on company. While other cloud-communications companies have added business VoIP services as an afterthought, hosted VoIP is the heart of ShoreTel Sky.